Effect of the stabilizer on bubble stability and homogeneity of cement emulsified asphalt mortar in slab ballastless track

Abstract

Cement emulsified asphalt mortar (CAM) is a critical and complex engineering material for slab ballastless track. Since the bubble stability of fresh CAM is a crucial and potential property to determine the construction quality of hardened CAM on site, to improve the bubble stability of CAM, the effect of the stabilizer on bubble stability was studied and evaluated by the property indexes of the workability, fluidity, time-dependent loss of air content under simulating disturbance condition and segregation of CAM in lab and on site. Moreover, to research the actual engineering application effect of the stabilizer, the bonding strength and construction quality of CAM with and without the stabilizer were tested respectively by lifting the full-scale track slab above the CAM at the age of 14days on site along with the microstructure analysis on the interfacial morphology with SEM. Results showed that the stabilizer can enhance the consistency and improve the bubble stability of fresh CAM; reduce the segregation and improve the homogeneity of hardened CAM effectively. Moreover, the stabilizer can increase the interfacial bonding strength between the hardened CAM and the concrete bottom of track slab with fewer asphalt particles or bubbles of CAM floating up to the interfacial surface; improve the construction quality of CAM on site. Good agreements for the effect of the stabilizer have also been found between the simulating experiment result in laboratory and that on site. The effect of the stabilizer on bubble stability of CAM may be due to the three-dimensional network formed by long cellulose ether and associative polyurethane molecular chains of the stabilizer. Related model was briefly supposed. These findings show promising field applications of the stabilizer and also provide a valuable reference for the preparation and construction quality control of CAM with high workability.